The Japanese film "Watch Tokyo Hot" was broadcast for 10 minutes on the advertising screen on Friday at a major intersection in the capital, leaving motorists variously amused or horrified.

The power was quickly shut off to the "videotron" -- as the giant screens are locally known -- but not before scenes of a couple engaged in a steamy tryst were captured on motorists' phones and went viral on social media.

Police and cybercrime specialists in the largely conservative, Muslim-majority country launched a hunt for the perpetrator and on Tuesday arrested a 24-year-old IT analyst in his office.

Access to pornographic websites is blocked in Indonesia, and romantic scenes in films and television programmes are often blurred or cut altogether by state censors.

The arrested man, whose identity was not disclosed, has admitted responsibility for the crime, Jakarta police chief Mochamad Iriawan said.

He carried out the prank after spotting login details displayed on the billboard.

"The suspect claims he worked alone," Iriawan told reporters.

"But we are still investigating whether he was working alone, whether he had a particular motive, or whether he was just fooling around."

Police plan to charge the man with publicly displaying a porn film and displaying a film showing indecent scenes.